The present invention relates generally to electrical circuit breakers wherein a compressed gas is utilized to quench the arc which occurs across the contact elements of the breaker during separation thereof. More particularly, the invention relates to a circuit breaker wherein an internal duct is defined through at least one of the contact elements to define a flow path through which the quenching gas may flow during the quenching operation.
An electric circuit breaker has become known in the art operating in accordance with a compression system in which the flow of the quenching gas is generated by means of a system including bellows and a piston. The system is provided with a stationary contact having a nozzle-like internal duct and a movable contact element, with a cylinder arrangement being provided at the movable contact element which is interconnected by means of a duct with the quenching chamber in which the quenching site is situated. The cylinder area is engaged by a piston which, with respect to the stationary contact element, is, in principle, stationary. Upon breaking of the circuit, the movable contact element jointly with the cylinder system is removed from the stationary contact element, and the amount of gas situated within the cylinder system is compressed by the system of the bellows and the piston, and is thus rapidly fed to the quenching site.
A problem resulting in the operation of this device is that the device for driving the breaker must actuate not only the movable contact element but also the cylinder system of the piston and bellows arrangement. This means that the masses which must be moved are very great, thereby requiring elevated driving power.
Moreover, there is known in the art an electrical circuit breaker having a piston and bellows arrangement wherein two opposite contact elements are provided with internal ducts designed as nozzles tightly surrounded by a movable contact system. The two contact elements and the contact system itself are surrounded by a blasting cylinder serving to generate flow of quenching gas. In the course of the breaking motion, the blasting cylinder connected with the movable contact system is moved over a stationary blasting piston and the occluded quenching gas is rapidly compressed. The powerful gas flow occurring following contact breaking blasts the arc which must however be reversed on the two stationary contact elements. It is particularly this last-mentioned feature that constitutes one of the major drawbacks of such a system, in view of the fact that communication entails particular problems. Moreover, the hermetic connection of the one stationary contact element with the movable contact system causes problems. In addition, the simultaneous actuation of the blasting cylinder and of the movable contact system requires relatively high driving power.
The present invention is aimed toward an electric circuit breaker of the type described above which would obviate the drawbacks of circuit breakers known in the art. In particular, the invention is directed toward reducing the driving power required for the movable contact element and for the blasting piston arrangement.